using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using JGSY.CMS.LowCode.Platform.Application.DTOs;
using JGSY.CMS.LowCode.Platform.Application.Interfaces;

namespace JGSY.CMS.LowCode.Platform.Application.Services
{
    /// <summary>
    /// 角色应用服务实现
    /// 提供系统角色的完整权限管理，包括角色创建、权限分配、用户授权、继承关系等功能
    /// 支持基于角色的访问控制(RBAC)、动态权限管理、角色层级结构等企业级安全需求
    /// 集成权限模板、批量授权、审计日志等高级权限管理特性
    /// </summary>
    public class RoleAppService : IRoleAppService
    {
        /// <summary>
        /// 日志记录器
        /// </summary>
        private readonly ILogger<RoleAppService> _logger;
        
        /// <summary>
        /// 角色数据集合（内存存储）
        /// 临时数据存储，生产环境应使用数据库持久化
        /// </summary>
        private static readonly List<RoleDto> _roles = new();
        
        /// <summary>
        /// 下一个角色ID计数器
        /// 用于生成唯一的角色标识符
        /// </summary>
        private static long _nextId = 1;

        /// <summary>
        /// 初始化角色应用服务实例
        /// </summary>
        /// <param name="logger">日志记录器</param>
        /// <exception cref="ArgumentNullException">当logger为null时抛出</exception>
        public RoleAppService(ILogger<RoleAppService> logger)
        {
            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
            InitializeSampleData();
        }

        /// <summary>
        /// 获取所有角色列表
        /// 返回系统中所有可用的角色信息，按名称排序
        /// </summary>
        /// <returns>角色列表，按名称升序排列</returns>
        /// <exception cref="InvalidOperationException">当获取操作失败时抛出</exception>
        public async Task<IEnumerable<RoleDto>> GetAllAsync()
        {
            try
            {
                await Task.Delay(10);
                return _roles.OrderBy(x => x.Name);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting all roles");
                throw;
            }
        }

        /// <summary>
        /// 根据ID获取角色信息
        /// 根据角色标识符查询特定角色的详细信息
        /// </summary>
        /// <param name="id">角色标识符</param>
        /// <returns>角色信息，如果不存在则返回null</returns>
        /// <exception cref="ArgumentException">当id无效时抛出</exception>
        /// <exception cref="InvalidOperationException">当查询操作失败时抛出</exception>
        public async Task<RoleDto?> GetByIdAsync(long id)
        {
            try
            {
                await Task.Delay(10);
                return _roles.FirstOrDefault(x => x.Id == id);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting role by id {Id}", id);
                throw;
            }
        }

        public async Task AddAsync(RoleDto dto)
        {
            try
            {
                dto.Id = _nextId++;
                _roles.Add(dto);
                
                _logger.LogInformation("Role added successfully: {Id} - {Name}", dto.Id, dto.Name);
                await Task.Delay(10);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error adding role");
                throw;
            }
        }

        public async Task UpdateAsync(long id, RoleDto dto)
        {
            try
            {
                var existing = _roles.FirstOrDefault(x => x.Id == id);
                if (existing == null)
                    throw new ArgumentException($"Role with id {id} not found");

                existing.Name = dto.Name;
                existing.Description = dto.Description;
                existing.Permissions = dto.Permissions;

                _logger.LogInformation("Role updated successfully: {Id} - {Name}", id, existing.Name);
                await Task.Delay(10);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error updating role {Id}", id);
                throw;
            }
        }

        public async Task DeleteAsync(long id)
        {
            try
            {
                var existing = _roles.FirstOrDefault(x => x.Id == id);
                if (existing == null)
                {
                    _logger.LogWarning("Role with id {Id} not found for deletion", id);
                    return;
                }

                _roles.Remove(existing);
                _logger.LogInformation("Role deleted successfully: {Id}", id);
                await Task.Delay(10);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error deleting role {Id}", id);
                throw;
            }
        }

        public async Task AssignPermissionsAsync(long roleId, List<string> permissionIds)
        {
            try
            {
                _logger.LogInformation("Assigning {Count} permissions to role {RoleId}", permissionIds.Count, roleId);
                
                var role = _roles.FirstOrDefault(x => x.Id == roleId);
                if (role == null)
                {
                    throw new ArgumentException($"Role with id {roleId} not found");
                }

                // 在实际实现中，这里应该根据permissionIds创建PermissionDto对象
                // 简化实现，清空现有权限并添加新权限
                role.Permissions.Clear();
                foreach (var permissionId in permissionIds)
                {
                    role.Permissions.Add(new PermissionDto 
                    { 
                        Id = long.Parse(permissionId),
                        Name = $"Permission_{permissionId}",
                        Description = $"Permission with ID {permissionId}",
                        Resource = "General"
                    });
                }

                await Task.Delay(10);
                _logger.LogInformation("Permissions assigned successfully to role {RoleId}", roleId);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error assigning permissions to role {RoleId}", roleId);
                throw;
            }
        }

        public async Task<IEnumerable<PermissionDto>> GetPermissionsAsync(long roleId)
        {
            try
            {
                await Task.Delay(10);
                
                var role = _roles.FirstOrDefault(x => x.Id == roleId);
                if (role == null)
                {
                    return Enumerable.Empty<PermissionDto>();
                }

                return role.Permissions;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting permissions for role {RoleId}", roleId);
                throw;
            }
        }

        private void InitializeSampleData()
        {
            if (_roles.Any()) return;

            _roles.AddRange(new List<RoleDto>
            {
                new RoleDto
                {
                    Id = _nextId++,
                    Name = "Administrator",
                    Description = "系统管理员，拥有所有权限",
                    Permissions = new List<PermissionDto>
                    {
                        new PermissionDto { Id = 1, Name = "SystemManage", Description = "系统管理", Resource = "System" },
                        new PermissionDto { Id = 2, Name = "UserManage", Description = "用户管理", Resource = "User" }
                    }
                },
                new RoleDto
                {
                    Id = _nextId++,
                    Name = "Editor",
                    Description = "内容编辑者，可以创建和编辑内容",
                    Permissions = new List<PermissionDto>
                    {
                        new PermissionDto { Id = 3, Name = "ContentRead", Description = "内容读取", Resource = "Content" },
                        new PermissionDto { Id = 4, Name = "ContentWrite", Description = "内容编辑", Resource = "Content" }
                    }
                },
                new RoleDto
                {
                    Id = _nextId++,
                    Name = "User",
                    Description = "普通用户，基础权限",
                    Permissions = new List<PermissionDto>
                    {
                        new PermissionDto { Id = 5, Name = "ContentRead", Description = "内容读取", Resource = "Content" }
                    }
                },
                new RoleDto
                {
                    Id = _nextId++,
                    Name = "Guest",
                    Description = "访客用户，只读权限",
                    Permissions = new List<PermissionDto>()
                }
            });
        }
    }
}
